COPD: disruption of the respiratory microbiota

The respiratory flora of individuals suffering from chronic obstructive pulmonary disease is less diverse than that of healthy individuals, and that seems to worsen as the disease progresses, according to a Swiss team.

Chronic cough, sputum and shortness of breath are the main signs of chronic obstructive pulmonary disease (COPD), which affects more than 3 million people in France and is characterized by progressive obstruction of airways. Patients who have this condition are more at risk of respiratory failure, as well as pulmonary infections.

Progressive disruption of the microbiota

To what extent are the bacteria that populate the lungs and respiratory tract affected by the disease? To answer this question, a team of researchers examined the microbial composition of the respiratory tract in different locations (pharynx, trachea, bronchi, lungs) in 32 individuals with COPD, then compared this composition to that of 10 healthy volunteers. In comparison with healthy individuals and patients in the early stages of the disease, patients suffering from severe COPD displayed an identical bacterial abundance but lower diversity and a different microbial composition, very heterogeneous across patients. This criterion could be used as a marker to assess the level of disease progression, even if samples taken along the respiratory tract were observed to be relatively homogeneous in the same individual.

Involvement of the immune system

The results also showed that the imbalance of the respiratory microbiota seemed to be associated with a greater abundance of some immune system cells (including molecules responsible for inflammation) in patients suffering from severe COPD, although the causal link between microbial imbalance (dysbiosis) and the disease still has to be elucidated. Taking into account the disruptions of this microbiota associated with an immune disorder may enable a better understanding of COPD and aggravating factors.